Speed-regulator for electric motors.



L. BRADLEY SPEED REGULATOR FOR ELECTRIC MOTORS.

APPLICATION FILED mums, 1913.

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WITNESSES: IN YENTOR ATTQRNE v.3

mm 'M a v v Patented July 8,1913.

L. BRADLEY. SPEED REGULATOR FOR BLEGTRIG mowons.

APPLIOATION FILED MAR. 3, 1913. 1,066,580, Patented July 8,1913.

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A TTORNE Y5 LQBRADLEY. SPEED REGULATOR FOB. ELECTRIC MOTORS.

APPLIUATION FILED MAB. 3, 1913. 1,066,580.. Patented July 1 s SHEETS-SHEET 3:

WITNESSES: IN VEN TOR W? g, y

I ATTORNEY? LYNDE BRADLEY, or MILWAUKEE,- wIscoNsIN.

SPEED-REGULATOR FOR ELECTRIC MOTORS.

Specification of Letters Patent.

Patented July 8, 1913.

Application filed March 3, 1913. Serial No. 751,973.

. field circuits, not only by adding or subtracting resistance units to secure step by step variations, but by employing c0mpres sible resistance members or units which permit of gradual variations in the resistance of the individual members, whereby units at maximum compression and minimum resistance may bemtroduced into the field circuit of the motor and the compression subsequently reduced to gradually increase the resistance; also to provide means whereby the actuating member upon which such resistance variations depend, will be automatically retained (at least in one stage of its movement) at any point of manual adjustment during power (current) maintenance and returned either to the point of when the current is.

greatest compression interrupted, or past that point to position of cutout; also to provide means whereby part the efiect of a glven adjustment. upon the field is kept constant notwithstanding temperature variations in the units.

In the drawings Figure 1 is a tront elevation of a compound speed regulator embodying my invention. Fig. 2 is a side view in section with frame omitted. Fig. 3 is a diagram of the electrical connections. Fig. 4 is a rear elevation showing the resistance varying pressure columns.

Like parts are identified by the same reference characters throughout thev several views.

The resistancemembers A, B, C and D consist of carbon columns similar to those shown and described in my former patent, Number 815317, dated March 13th, 1906;-

In the present construction, the operating lever E, (Fig. 1), actuates crank disk F (Fig. 2), and the rotary movement of the crank 'Fis transmitted to apply a varying pressure upon the columns through link rod G, bar H and equalizer bars I, the-latter having their end portions in bearing contact with end caps The lever E normally occupies a substantially vertical position. As 1t swings upwardly to and past the horizontal position, it moves'successively over contacts L, M and N of the armature circuit;

also over se inent O andcontacts P, Q, and R of the field circuit, and also over dead segment S to contact T of the circuit of the release magnet, presently described. A spring E restores the lever to normal position when not otherwise held in another position of adjustment. The current isintroduced through the lever E. When the lever connects with contact segment L, the armature circuit is from lever to segment L through armature resistance column, (assumed to be column A in Fig. 3), armature, and from armature to line. The field circuit 'is' simultaneously established from lever to segment 0, thence directly to field and to line. As lever E moves upwardly, the pressure upon the carbon columns is'gradually increased as crank F swings to line of centers, whereupon the pressure is at maximum. Meanwhile lever E moves from segment L to contact M-to short circuit armature resistance column A at maximum pressure and minimum resistance, quired speed. The continued movement of lever E then makes contact successively with contact buttons P and Q and contact seg-- ment R to successively introduce the resist-ance columns B, C and D into the field circuit while their resistance is substantially at minimum. A continued movement of lever E over segment It will then progressi'vely increase the resistance in all three columns, since crank F will have passed the line of centers from crank through the axis of crank disk rotation and the connection of rod G with bar H and the pull upon bar H will therefore be relieved as the crank moves in this direction. Preparatory to switching in the initial field resistance by the movement of lever E to button P, the lever E moves from dead the armature having by this time acenergy to hold lever E in any position of adjustment along segment T, against the tension of spring E. But in case of an inspring IE will instantly restore it to normal.

But when the armature resistance .column is cut out and the field resistance switched in, the coil is effective to hold the lever at any desired point of adjustment, and the speed of the motor can bevery accurately controlled by merely varying the pressure upon the columns without introducing additional units. This statement, however, assumes that the resistance of the columns A, B, C and 1) will be uniform in any given position of lever adjustment, and it is therefore necessary to take into account the heat generated in the columns themselves, whereby there is a tendency to decrease the resistance automatically after .the lever has been brought to the desired position of adjustment. The cap J at one end of each column opposite theend at which the lever pressure is applied, is caused to bear against a stop J "carried by a rod B which extends through the column and connects .with a fixed abutment b. The unconnected ends of the rods B beyond the stops J are provided withvsuitable guidebearings at b.

The rods B are electrically insulated from the disks or other members composing the columns. They are formed of a material which expands when heated, and since these rods are exposed to the heat electrically generated in the columns, it is obvious that as the heatincreases, the rods will lengthenr The extent to which the rods will lengthen with each added degree of heat depends u on the character of the 'material emp oyed, and byusing proper alloys, it is possible to provide rods which will expand and reduce the pressure upon the columns in such proportion to the increased heat that the resistance of said columns will remain substantially constant. The decrease in electrical resistance of each-column, due to heat, will thus be compensated by an increased electrical resistance therein due to a reduction in pressure by-the lengthening of the rod Bk. It is therefore possible to adjust a stage of operation of this regulator, a variablearmature resistance is secured by varying the pressure upon a resistance column,

the pressure being relieved and the resistance raised to maximum automatically whenever the lever employed for efl'ecting the compression is released. In the other stage, the *pressure upon the columns starts cuit, and so far as this stage of operation is concerned, the compression means is held at any desired stage of compression so long as the release magnet is energized, and swings automatically to the point of greatest compression when released by said magnet.

The fact that the operating lever or comg5 pressing means moves past the point of greatest compression to its normal position with the compression reduced, is of no importance'so far as the field circuit is concerned since the resistance in the field circuit is wholly cut out when the lever passes said point of greatest compression on its return to normal.

I claim g 1 The combination with an electric motor, of means for introducing a compressible resistancecolumn into the circuit of the adapted to cut out such unit and connect unitssuccessively into the field circuit of the motor during the stage of high compression.

3. The combination withan electric motor, of a-set of compressible resistance units, an actuator movable from a position of initial low compression through a stage of high compression to a final stage of low compression of said units, and switch mechanism for connecting one ofsaid units in the armature circuit of the motor during the initial stage of low compression, and also adapted e 'to cut out such unit and connect units suc-.

cessively into the field circuit of the motor during the stage of high compression, each of said units having 'a thermally expansible member and means for utilizing the expansion and retractionof said member to vary expansion and contraction to offset the effect of various temperatures upon the conductivity of the unit.

4. In combination with an electric motor having a field and an armature, a compressible resistance medium in series with said field, means for varying the'pressure on said resistance medium, a release magnet adapted to hold said compression means at any stage of its action, and means for moving said compression means to its position of greatest compression when released by said magnet and then cutting out the resistance medium from said field.

5. In an electric current. controller, the combination of a compressible resistance medium and means for varying the pressure on said medium, an electromagnet adapted to resist the action of said compression means when said electromagnet is energized.

6. In an electric current controller, the, combination of a compressible resistance, nedium and means for varying the pressure on said medium, an electromagnet adapted to resist the action of said compression means when said electromagnet -is energized, and means for switching the resistance medium into circuit with the field of an electric motor at the stage of greatest pressure and subsequently reducing said pressure with the resistance medium in circuit with said field. v

'7. In an electric current controller, the combination of a compressible resistance medium and means for varying the pressure on said medium, an electromagnet adapted to resist the action of said compression means when said electromagnet is energized, means for switching the resistance medium into circuit with the field of an electric motorat the stage of greatest pressure and subsequently reducing said pressure with the resistance medium in circuit with said field, and means for cutting out said magnet and also the resistance in sequence in case the current is interrupted.

8-. In an electric current controller, the combination ofa compressible resistance medium, means for varying the pressure on retard the action of said pressure means during one stage of its movement, and means adapted to return said compression means said medium, a release magnet adapted to to its initial position when released by said magnet. -="-varying the pressure on said resistance me- ,9. In an electric current controller, the combination with a set of compressible resistance columns, a motor having an armature adapted to be connected in circuit with one of the columns, and its field adapted to be connected in circuit with another of said columns, a lever for applying pressure tothe columns, a magnetic brake controlling said lever in one stage of its movement, and means for utilizing the lever to set said magsaid compression means netic brake, said lever being arranged to move in either directionthrough a sta e of increasing compression to a stage oi: decreasing compression, whereby the resistance of said columns may be decreased to a connecting and disconnecting point and subsequently increased.

10. In combination with ah electrical cir-' cuit, a set of compressible resistance columns, a movable actuating member for connecting and disconnecting said columns in said circuit at the stage of greatest pressure, said actuating member being adapted to move through a stage of decreasing compression at both sides of the stage of greatest pressure, means for automatically restoring the actuating member to normal position, and :a magnetic brake adapted, when energized, to prevent the operation of the restoring means during one of said stages.

11. In combination with an electrical circuit, a set of compressible resistance columns, a movable actuating member for connect-ing and disconnecting said columns in said circuit at the stage of greatest pressure, said actuating member being adapted to move through a stage of decreasing compression at both sides of the stage of greatest pressure, means for automatically restoring the actuating member to normal position, and a magnetic brake adapted, ,when energized, to prevent the operation of the restoringmeans during one of said stages, together with means for automatically varying the pressure upon said columns in accordance with variations in temperature and in such proportions as to. maintain a constant electrical resistance for any given position of the actuating member.

12. In combination with an electric motor having a field and an armature, a compressible resistance medium in series with said field, means for varying the resistance by varying the pressure on said'resistance medium, a release mechanism adapted to hold said compression means at any stage of its action, and means for returning said compressing means in the direction of increased compression when released by said mechanism. I v

13. In combination with an electric motor having a field and an armature, a compressible resistance medium in series with said field, means for varying the resistance by dium, a release mechanism adapted to hold at any stage of its and means for returning said comaction,

the direction of increased pressing means in compression nism, together with means for maintaining aconstant'electrical resistance in said me--' dium under varying temperaturesthereof.

- 14. In combination with an electric motor having a field and an armature, a'compressible resistance medium in series with said.-

when released by said med afield, means for varying the pressure on said resistance medium, a release magnet adapted to hold said compression means at any stage of its action, and means for moving said compression means to its position of greatest compression when released by said magnet.

15. In combination with an electric motor,-

a compressible resistance medium in series with the field of said motor, means for varying the resistance by varying the pressure on said resistance medium, and means for moving said compressing means in the direction of increased compression during the initial part of its movement toward normal position.

16. In combination with an electric motor, a compressible resistance medlum 1n serles with the field of said motor, means for in any given position of manual adjustment.-

In testimony whereof I aflix my signature in the presence of two witnesses. V,

. LYNDE BRADLEY. Witnesses:

- LEVERE'I'I C. WHEELER,

IRMA D. BREMER. 

